1. Field of the Invention
The field of art to which this invention pertains may be generally located in the class of devices relating to sink strainers. Class 4, Subclass 286, Sink Strainers and Stoppers United States Patent Office Classification, appears to be the applicable general area of art to which the subject matter similar to this invention has been classified in the past.
2. Description of the Prior Art
This invention relates to sink strainers, and more particularly to the type of sink strainer used with kitchen sinks or the like. Sink strainers of the type to which this invention is directed generally include a substantially large body in which is seated a basket strainer having a rubber stopper. The basket strainers are adapted to be moved manually between opened and closed positions to permit draining and filling of the sink. Heretofore, basket strainers of this type have relied on the weight of the water in the sink to push the basket strainer's rubber stopper against the strainer body to prevent leakage of water from the sink when it is desired to retain water in the sink. However, it has been found that the weight of water in the sink does not create enough downward force to provide a leakproof seal, and accordingly, there is always some leakage by such prior art basket strainers. Heretofore, attempts have been made to provide a strainer basket or crumb cup which has a valve disc that is adapted to seat and close the drain opening in the strainer upon rotational movement of a valve stem in one direction, and conversely to open the drain upon a rotational movement of the valve stem in the opposite direction. The last mentioned type of sink strainer structure is shown in the prior art U.S. Pat. No. 2,890,463. A disadvantage of the prior art sink strainer is that it is expensive to make because the valve disc must be machined to seat on a machined surface in the sink strainer to provide a metal to metal seating seal which will not leak. A further disadvantage is that most sink strainers are made with a stamped body and the metal valve disc employed in the last mentioned patent is not capable of providing a leakproof metal to metal seating seal with such a stamped sink strainer body.